Model for Interference between Direct and Rreflected Rays
A model for the intensity of the received signal (modulated carrier) based on the interference of a directly transmitted ray and a reflected ray. Parameters A and B govern the amplitude of the two signals, and F is their relative phase, varying with the water depth. A coherence factor a represents the degree to which the 10-cycle modulation "bits" from one ray overlaps those of the other.

The calculated curve is the result of varying the height of the transducers (not very well known) to get the best fit. The fit is qualitatively good, but in detail not correct.